Method and apparatus for extruding metal powder to produce a continuous rod

ABSTRACT

There is disclosed an apparatus for the continuous extrusion of copper rod from copper powder in a manner which prevents harmful deterioration of the compacting cylinder and requires the expenditure of less power to operate.

iilrafitedl Stems ?a1em11 [1 1 Roberts Sept. 11, 1973 I METHOE) ANDAPPARATUS FOR 3,293,006 12/1966 Bartz 264/111 X EXTRUDHNG METAL POWDER 03,060,560 10/1962 Biehl et a1.... 29/4205 3,189,988 6/1965 Crane 29/4205PRODUCE A CONTINUOUS ROD 1,174,646 3/1916 Williams... 425/78 X [75]Inventor: Edward S. Roberts, New York, 2,964,177 12/1960 Scribner 72/259Primar Examiner-Charles W. Lanham 73 A T d 11 C N Y k, y I I Sslgnee we("poi-mum ew or Assistant ExaminerD. C. Reiley, I11

' Attorney-Pennie, Edmonds, Morton, Taylor & Adams 122] Filed: Jan. 27,1971 I N 110,236 mi 0 57 ABSTRACT 52] U5, (:1 29 4205 29/DIG 31 29 7There is disclosed an apparatus for the continuous ex- 2 4 1 1 45/73trusion of copper rod from copper powder in a manner {51 1 1111. C132213/24 which prevents h rm l eterior tion of the C mpact- [58] Fieldof Search 264/1 1 1; 29/420, g cylinder and equire the expenditure ofless power 29/4205, DIG. 47, DIG. 31; 425/78 to p 56] References Cited 8Claims, 6 Drawing Figures UNITED STATES PATENTS 2,902,714 9/1959 Johnson264/111 X PATENTED SEPI H915 SHEET 2 OF 4 EEC:

INVENTOR. EDWARD S. ROBERTS 7? z%a&%

ATTORNEYS PATE'NIED 3,757. 410

sum 3 or 4 FIG3 INVENTOR. EDWARD s. ROBERTS ATTORNEYS METHOD ANDAPPARATUS FOR EXTRUDING METAL POWDER TO PRODUCE A CONTINUOUS RODBACKGROUND OF THE INVENTION It is known to extrude metal powders bysuccessive compacting and extruding. However, successful operations haverequired canning of the metal powders to permit the outside of the canto be lubricated. This helps to prevent metal powder from being caughtbetween the extrusion ram and the compacting cylinder wall which wouldcause galling. This method of extrusion, however, permits only batchoperation and is limited by the amount of metal that can be loaded intoa cam and which can be placed in the extrusion cylinder and finallyexpressed through a die.

It would be highly desirable to extrude copper powder into the form, sayof a /16 inch diameter rod which can easily be drawn into wire.Moreover, it would be desirable to extrude a rod long enough to weightup to to tons. This would permit coiling the rod into a bundle forannealing, if need be, before drawing into any desirable length of wire.Such an operation is impossible with canned material.

It is the purpose of the present invention to provide unique means forprocessing metal powder which will solve the above problem.

SUMMARY OF THE INVENTION In accordance with the present invention,apparatus is provided for receiving a measured quantity of metal powder,such as copper in a compacting cylinder. During transmission of (undervacuum) the powder to the chamber a rarefied hydrogen atmosphere ismaintained to prevent oxides from forming and to inhibit the suspensionof particles in the atmosphere. Such oxides or particles would be likelyto cause galling of the cylinder wall during subsequent compacting. Afirst ram means is provided for compacting the powder to a sufficientdensity for extruding. Thereafter second ram means forces an extrudingdie through the compacted powder in a direction opposite to thecompacting direction to cause extrusion of copper rod in any suitablelength. This two state arrangement reduces the overall powerrequirements of the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a flow diagram of acompacting extrusion apparatus constructed in accordance with thepresent invention; I

FIG. 2 is an elevational view of an extruder in accordance with thepresent invention;

FIG. 3 is an enlarged cross-sectional detail of a portion of theapparatus of FIG. 2 wherein metal powder is admitted to the compactingcylinder;

FIG. 4 is similar to FIG. 3 showing the action of the compacting ram;

FIG. 5 is similar to FIG. 3 and shows the action of the extrusion ramand die; and

FIG. 6 is similar to FIG. 3 and shows the return of the ram cylinder toits initial position.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing andinitially to FIG. 1, an apparatus constructed in accordance with theprinciples of the invention has been illustrated. The apparatus includesa tooth mill 10 adapted to receive briquettes or other consolidated orpartially consolidated masses of copper or other metal powder from aproduction source. Such briquettes or lumps of consolidated powder areground in the mill into powder. A reducing hydrogen atmosphere isadvantageously maintained in the mill to prevent the possible formationof oxides which would otherwise occur in the presence of normalatmosphere.

From the mill 10 the metal powder (hereinafter referred to as copperpowder) may proceed through 'conduits II, and 12b to lock hoppers I3 andI4. Fluidtight valves 15a, 15b control the admission of powder tr thehoppers. Conduits 16a, 16b having fluid valves 17a, 17b therin furthercontrol the admission of powder to a conduit which leads to a feeder 18.The latter has a thick horizontal disk 19 provided with verticalpassages 19a, 19b, 19c etc. As the disk rotates each passage 19a etc.becomes filled with a measured quantity of powder and further rotationcauses the powder to be discharged through a conduit 41 leading to theextruder of the invention. Means (not shown) are provided for exhaustingmost of the hydrogen from hoppers 13 and 14 and from feeder 19 for areason which will be explained.

An extruder 20 constructed according to the principles of the inventionhas been illustrated in FIGS. 2-6. The extruder 20 comprises a mainframe having two upright side members 21 and 22 joined by a base 23 andintermediate across members 24, 25, 26. The side members 21 and 22define a centrally located well for the mounting of hydraulic compactingand extrusion means.

Accordingly, a first hydraulic cylinder 27 is secured by mounting plate28 and peripheral bolts 29 to the underside of cross arm 25. A secondhydraulic cylinder 30 is similarly secured by mounting plate 31 andbolts 32 to the upper portion of cross arm 25. A cylindrical container33 is secured beneath cross arm 24 by mounting plate 34 and bolts 36.The latter have ends 36a which engage in T-slots 37 permitting somelateral adjustment.

The container 33 defines a cylindrical bore 38 which receives acompacting ram 39 extending from and actuated by hydraulic cylinder 27.Bore 38 forms a compacting chamber 40 which connects with a conduit 41leading from feeder 19. The lower end of bore 38 is closed by anextrusion die 42 having in its upper end an orifice 42a. Die orifice 42aconnects with an extrusion passage 44 in the die support 43 which isperipherally mounted to a yoke 86 by a plate 47 and bolts 48. The yoke46 in turn is secured to rods 49, 50 which extend through side members21 and 22 to be connected to an upper yoke 51. The latter yoke 51 andthus the lower yoke 46 are driven by hydraulic cylinder 30. Stop means53 limits the uppermost travel of yokes 51 and 46.

Referring now to FIGS. 3 to 6, it will be seen that a measured quantityof metal powder. 55, such as copper will first be charged within thecompacting chamber 40 through conduit 41 connected to feeder 18 ofFIG. 1. The powder 55 will be admitted to the chamber 40 in a nearvacuum containing a residual hydrogen atmosphere. The hydrogenatmosphere is mostly evacuated in order to prevent the creation of acloud of metal powder during charging of chamber 40 and duringcompacting by ram 39 in order to prevent particles from entering betweenthe cylindrical wall of chamber 40 and the ram 39 and also to avoidhaving to compress a gas atmosphere to high pressure during thecompaction operation.

FIG. 3 is an enlarged detail of the compacting cylinder 40 formed withinthe container 33 wherein a measured quantity of copper powder 55 hasbeen deposited through conduit 41. FIG. 4 shows the movement of the ram39 to effect partial compaction of the metal powder 55. FIG. 5 shows thedie support 43 and die mount 42 thrust upwardly by actuation of cylinder30 and upward movement of yoke 46 to extrude compacted powder throughdie orifice 42a and to form a copper rod 60. FIG. 6 shows the returnmovement of ram 39 preparatory to permitting chamber 40 to be recharged.

The reasons for the above described inverted extrusion may be stated asfollows:

In the compaction of metal powder in a cylinder with a ram there is agradient pressure downward from the face of the moving ram toward theface of the fixed die on the opposite side of the metal powder billet.For the prior art method of direct extrusion there would be an orificein this fixed die opposite to the ram. To extrude the compact throughthis orifice it is necessary to exert a pressure on the ram which is thepressure for compaction in addition to the pressure which is requiredfor extrusion.

According to the present invention the feature of inverted extrusion isachieved by placing the extrusion orifice within an extrusion ram whichis activated, as described above, after the compacting ram hassubstantially completed its compaction stroke. As the extrusion ram ismoved into the metal billet thev pressure gradient is in the directionopposite to that during compaction so that the maximum pressure is atthe extrusion orifice. The length of the extrusion stroke can be keptsmall to keep all ram travel distances to a minimum.

By way of comparison, the design of direct extrusion is based on;

F KA In R where: V

F force on the ram in lbs.

K extrusion constant in psi.

A area of the cylinder in sq. g

R extrusion ratio A/a where: a area of theextruded rod in sq. ins. Forcop per:

Temp. "F i v l800 10,000 I400 20,000 I000 30,000 800 35,000 600 42,000400 48,000 200 4,000 l00 57,CK)0

force may represent friction between the billet and the cylinder, or, ifthe metal to be extruded welds to the cylinder wall, it represents theshearing force required to shear the metal of the billet. The metal ofthe billet can also weld to the ram surface. If the billet metal slidesin the cylinder the force required to slide the billet, F is linearlyproportional to the product of the surface area A and the unit pressureat the surface P: F= u AP. If P is constant then F RA. If the billetmetal welds to the cylinder F would also be proportional to A above.

In direct extrusion of a billet the force required on the ram generallydecreases as the billet is extruded, the decrement being roughlyproportional to the reductionin cylindrical surface area of the billetremaining in the cylinder, until the billet length is reduced to somefraction of the cylinder diameter at which time the force for extrusionalone apparently mounts. This de crease in force as extrusion of abillet proceeds is not found with inverse extrusion and the forcerequired on the ram is lower than in direct extrusion and remainsconstant as extrusion proceeds.

From these relations it would appear that if we compact with the top ram39 and extrude inversely with the bottom die 42 extrusion will not occurbetwen the top ram and the cylinder wall. Moreover, if the clearancebetween the ram andthe cylinder and between the die and the cylinder is0.001 inch then the ratio of this clearance area to the extrusion areaof the 5/16 inch dia. hole in the die is 19.53 and In R would be 5.74instead of 2.77 requiring a cylinder pressure 2.07 times as high toextrude copper directly through the clearance space as would be the caseinvertedly through the die.

It will be apparent therefore that the present invention provides forsuccessful continuousrod extrusion from compacted metal powder becauseof certain unique features which have been described. Firstly, bymaintaining a rarefied hydrogen atmosphere in the compacting cylinder,the formation of oxides are prevented as well as the suspension ofcopper particles which might with oxides cause galling of the cylinderwall. This is a very important feature since thepowder need .not inanyway be lubricated. Secondly, the amount of power necessary tocompactand extrudeis made optimum by the inverted extrusion technique. Muchgreater power would be required if the compacting ram had to accomplishalso the extrusion of the rod. The invention thus provides a method andmeans for producing high quantity metal rod continuously under optimumpower consumption. 7

It will be understood that the foregoing description isof a preferredembodiment of the invention and is therefore representative. In order toappreciate fully the scope of the invention reference should be made tor extrusion and means for extruding said powder from a compacted statecomprising a die, first ram means for compacting said powder in adirection toward said die during its compaction stroke and second rammeans containing said die for extruding said rod in a direction oppositeto said compacting direction, said second ram means being activatedafter the first ram means has substantially completed its compactionstroke.

2. The apparatus of claim 1 wherein said atmosphere is hydrogen gas andwherein the apparatus further includes mill means for receivingbriquettes and like consolidated masses of metal powder for conversionin the presence of hydrogen gas into powder form, and feeder means forreceiving said powder and for discharging a measured quantity of metalpowder into said compacting chamber.

3. A method of extruding a metal powder in the form of a continuousdense solid elongated shape which comprises flowing a charge of metalpowder in a protective gaseous atmosphere into an extrusion chamber, thegaseous atmosphere being substantially completely evaucated from saidchamber, compacting the powder by compressing it towards an extrusiondie and then extruding the compacted mass from said chamber through saiddie by pressing the extrusion die into the mass.

4. The method according to claim 3 wherein the residual gaseousatmosphere in the evacuated extrusion chamber is non-oxidizing.

5. The method according to claim 4 wherein the gas is hydrogen.

6. The method of extruding a metal powder in the form of a continuousdense solid elongated rod which comprises the steps of: maintaining anatmosphere whch is substantially inert with respect to a metal to beconverted to powder in a mill, converting said metal into a powder inthe presence of said atmosphere, accumulating said powder in a collectorin continued presence of said atmosphere, evacuating said collector andextrusion chamber connected thereto to leave only a residual atmosphere,flowing a charge of metal powder into said extrusion chamber, compactingsaid powder by compressing it towards an extrusion die and thenextruding the compacted mass from said chamber through said die bypassing the extrusion die into said mass.

7. The method according to claim 6 wherein the residual gaseousatmosphere in the evacuated extrusion chamber is non-oxidizing.

8. The method according to claim 7 wherein the gas is hydrogen.

a: a: a:

UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION Patent No.2.757J-ll0 Dated September 11, 1973 Inventor(s) It is certified thaterror appears in theabove-identified patent am that said Letters Patentare hereby corrected as shown below:

Column 1, line 21, 7 "weight up to 10 to 20" should read "weigh up to 10to 2 0';

Column 2, line l t, "tr the hoppers" should read --to the hoppers--Column 2, line l5, "17b therin further" should read --l7b thereinfurther-; a

Column 6,, line 9 "whch is substantially" should read --which issubstantially--;

Signed and sealed this 1st day of January 1974.

(SEAL) Attest;

EDWARD M.FLET( IHER,JR. RENE D. TEGTMEYER Attestlng Officer ActingCommissioner of Patents Us COMM-DC 60376-P69 i 0.8. GOVIINIINT "Irma;ornci a! o-au-Ju.

F ORM PC4050 (10-69) NITED STATES PATENT OFFICE CERTIFICATE OF.CQRRECTION Patent No. 2,7 7,410 Dated September 11, 1973 Inventor(Edward S. Roberts I: is certified that error appears in theaboveidentified patent and that said Letters Patent are hereby correctedas shown below:

Column 1, line 21,. "weight up to 10 to 20" should read --weigh up to 10to 20 '-3 7 Column 2, line 1 k, "tr the hoppers" should read --to thehoppers-- Column 2, line 15, "17b therin further" should read '--17b'therein further-; I is Column 6, A line 9' "whch is substantially"should read --which is substantially";

Signed and sealed this 1st day of January 1974.

(SEAL) Attest:

EDWARD M.FLETC IHBR,JR. v RE NE D. TEGTMEYER Attesting Officer ActingCommissioner of Patents

2. The apparatus of claim 1 wherein said atmosphere is hydrogen gas andwherein the apparatus further includes mill means for receivingbriquettes and like consolidated masses of metal powder for conversionin the presence of hydrogen gas into powder form, and feeder means forreceiving said powder and for discharging a measured quantity of metalpowder into said compacting chamber.
 3. A method of extruding a metalpowder in the form of a continuous dense solid elongated shape whichcomprises flowing a charge of metal powder in a protective gaseousatmosphere into an extrusion chamber, the gaseous atmosphere beingsubstantially completely evaucated from said chamber, compacting thepowder by compressing it towards an extrusion die and then extruding thecompacted mass from said chamber through said die by pressing theextrusion die into the mass.
 4. The method according to claim 3 whereinthe residual gaseous atmosphere in the evacuated extrusion chamber isnon-oxidizing.
 5. The method according to claim 4 wherein the gas ishydrogen.
 6. The method of extruding a metal powder in the form of acontinuous dense solid elongated rod which comprises the steps of:maintaining an atmosphere whch is substantially inert with respect to ametal to be converted to powder in a mill, converting said metal into apowder in the presence of said atmosphere, accumulating said powder in acollector in continued presence of said atmosphere, evacuating saidcollector and extrusion chamber connected thereto to leave only aresidual atmosphere, flowing a charge of metal powder into saidextrusion chamber, compacting said powder by compressing it towards anextrusion die and then extruding the compacted mass from said chamberthrough said die by passing the extrusioN die into said mass.
 7. Themethod according to claim 6 wherein the residual gaseous atmosphere inthe evacuated extrusion chamber is non-oxidizing.
 8. The methodaccording to claim 7 wherein the gas is hydrogen.